Methane Oxidation, Production, and Emission at Contrasting Sites in a Boreal Bog
Dates
Year
2000
Citation
Whalen, S. C., and Reeburgh, W. S., 2000, Methane Oxidation, Production, and Emission at Contrasting Sites in a Boreal Bog: Geomicrobiology Journal, v. 17, no. 3, p. 237-251.
Summary
Boreal peatlands, a major source of atmospheric CH4 , are characterized by a rapidly fluctuating water table position and meter-scale variations in relief. Regional and ecosystem-based studies show that water table position generally controls CH4 emission from boreal peatlands by influencing the relative extent of the zones of CH4 oxidation and production within the peat profile. We used a combined field and laboratory study to assess the influence of local hydrology on the short-term dynamics of CH4 production, oxidation, and emission from sites in an Alaskan boreal peatland that were characterized by temporarily (site LB1A) and permanently (LB2) water-saturated subsurface peat during the thaw season. The two sites contrasted sharply [...]
Summary
Boreal peatlands, a major source of atmospheric CH4 , are characterized by a rapidly fluctuating water table position and meter-scale variations in relief. Regional and ecosystem-based studies show that water table position generally controls CH4 emission from boreal peatlands by influencing the relative extent of the zones of CH4 oxidation and production within the peat profile. We used a combined field and laboratory study to assess the influence of local hydrology on the short-term dynamics of CH4 production, oxidation, and emission from sites in an Alaskan boreal peatland that were characterized by temporarily (site LB1A) and permanently (LB2) water-saturated subsurface peat during the thaw season. The two sites contrasted sharply with respect to the dynamics of CH4 cycling. Site LB1A, which showed low CH4 concentrations in pore water ( concentrations in pore water ( concentrations in pore water (4 and CH4 diffusing upward from the saturated zone for a net flux of 0.9 mg CH4 per m2 per day. In contrast, LB2 had pore water CH4 concentrations, 300µM and emitted CH4 at 69mg per m2 per day . Roughly 55% of the CH4 diffusing upward from the saturated zone at LB2 was oxidized in transit to the peat surface. Methane oxidation potentials (Vox ) were maximum in the 10-cm zone immediately above the local water table at both sites but were greater on a dry mass (dw) basis at LB2 (498-650 ng CH4 per gdw per hour than at LB1A (220-233ng CH4 per gdw per hour. Methane production potentials (Vp) were low () were low (4 per gdw per hour at LB1A, but the maximum at LB2 (139ng CH4 per gdw per hour was spatially coupled with the maximum Vox. Methanogens exposed to O2 produced no CH4 in a subsequent 48 hour anoxic incubation, whereas methanotrophs incubated anoxically oxidized CH4 vigorously.